III-nitride multi-wavelength LED for visible light communication

ABSTRACT

A light emitting diode (LED) array may include a first pixel and a second pixel on a substrate. The first pixel and the second pixel may include one or more tunnel junctions on one or more LEDs. The LED array may include a first trench between the first pixel and the second pixel. The trench may extend to the substrate.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.17/010,300, filed on Sep. 2, 2020, which is a Continuation of U.S.application Ser. No. 16/228,311, filed on Dec. 20, 2018, which claimsthe benefit of U.S. Provisional Application No. 62/609,447 filed on Dec.22, 2017, U.S. Provisional Application No. 62/609,359 filed on Dec. 22,2017, European Patent Application No. 18163287.8 filed on Mar. 22, 2018,and European Patent Application No. 18163994.9 filed on Mar. 26, 2018,the contents of which are hereby incorporated by reference herein.

BACKGROUND

Micro-LEDs (uLEDs) may be small size LEDs (typically ˜50 um in diameteror smaller) that can be used to produce very high-resolution colordisplays when uLEDs of red, blue and green wavelengths may be aligned inclose proximity. Manufacture of an uLED display typically involvespicking singulated uLEDs from separate blue, green and red WL wafers andaligning them in alternating close proximity on the display. Due to thesmall size of each uLED, this picking, aligning, and attaching assemblysequence is slow and failure prone. Even worse, since improvingresolution generally requires decreasing uLED size, the intricacy anddifficulty in pick and place operations needed to populate a highresolution uLED display can make them too expensive for widespread use.

SUMMARY

A light emitting diode (LED) array may include a first pixel and asecond pixel on a substrate. The first pixel and the second pixel mayinclude one or more tunnel junctions on one or more LEDs. The LED arraymay include a first trench between the first pixel and the second pixel.The trench may extend to the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding can be had from the following description,given by way of example in conjunction with the accompanying drawingswherein:

FIG. 1A shows a multiple quantum well light emitting diode (LED);

FIG. 1B shows etching a first LED, a second LED, a third LED, a firsttunnel junction, and second tunnel junction to form one or morechannels;

FIG. 1C shows removing different portions of the first LED, the firsttunnel junction, the second LED, the second tunnel junction, and thethird LED;

FIG. 1D shows a third etching step may to further define pixels;

FIG. 1E shows forming a blanket conformal dielectric layer;

FIG. 1F shows forming openings in the conformal dielectric layer;

FIG. 1G shows forming contacts in the openings;

FIG. 1H shows forming another contact in an opening to form an LEDarray;

FIG. 1I shows attaching the LED array to an LED device attach region;

FIG. 1J shows another example of an LED array;

FIG. 1K shows the LED array forming a part of a visible lightcommunication (VLC) system;

FIG. 1L shows a VLC receiver;

FIG. 1M is a flowchart illustrating a method of use;

FIG. 1N is a flowchart illustrating a method of forming a device;

FIG. 2A is a diagram showing an Light Emitting Diode (LED) device;

FIG. 2B is a diagram showing an LED system with secondary optics;

FIG. 3 is a top view of an electronics board for an integrated LEDlighting system according to one embodiment;

FIG. 4A is a top view of the electronics board with LED array attachedto the substrate at the LED device attach region in one embodiment;

FIG. 4B is a diagram of one embodiment of a two channel integrated LEDlighting system with electronic components mounted on two surfaces of acircuit board; and

FIG. 5 is a diagram of an example application system.

DETAILED DESCRIPTION

Examples of different light illumination systems and/or light emittingdiode implementations will be described more fully hereinafter withreference to the accompanying drawings. These examples are not mutuallyexclusive, and features found in one example may be combined withfeatures found in one or more other examples to achieve additionalimplementations. Accordingly, it will be understood that the examplesshown in the accompanying drawings are provided for illustrativepurposes only and they are not intended to limit the disclosure in anyway. Like numbers refer to like elements throughout.

It will be understood that, although the terms first, second, third,etc. may be used herein to describe various elements, these elementsshould not be limited by these terms. These terms may be used todistinguish one element from another. For example, a first element maybe termed a second element and a second element may be termed a firstelement without departing from the scope of the present invention. Asused herein, the term “and/or” may include any and all combinations ofone or more of the associated listed items.

It will be understood that when an element such as a layer, region, orsubstrate is referred to as being “on” or extending “onto” anotherelement, it may be directly on or extend directly onto the other elementor intervening elements may also be present. In contrast, when anelement is referred to as being “directly on” or extending “directlyonto” another element, there may be no intervening elements present. Itwill also be understood that when an element is referred to as being“connected” or “coupled” to another element, it may be directlyconnected or coupled to the other element and/or connected or coupled tothe other element via one or more intervening elements. In contrast,when an element is referred to as being “directly connected” or“directly coupled” to another element, there are no intervening elementspresent between the element and the other element. It will be understoodthat these terms are intended to encompass different orientations of theelement in addition to any orientation depicted in the figures.

Relative terms such as “below,” “above,” “upper,”, “lower,” “horizontal”or “vertical” may be used herein to describe a relationship of oneelement, layer, or region to another element, layer, or region asillustrated in the figures. It will be understood that these terms areintended to encompass different orientations of the device in additionto the orientation depicted in the figures.

Semiconductor light emitting devices or optical power emitting devices,such as devices that emit ultraviolet (UV) or infrared (IR) opticalpower, are among the most efficient light sources currently available.These devices may include light emitting diodes, resonant cavity lightemitting diodes, vertical cavity laser diodes, edge emitting lasers, orthe like (hereinafter referred to as “LEDs”). Due to their compact sizeand lower power requirements, for example, LEDs may be attractivecandidates for many different applications. For example, they may beused as light sources (e.g., flash lights and camera flashes) forhand-held battery-powered devices, such as cameras and cell phones. Theymay also be used, for example, for automotive lighting, heads up display(HUD) lighting, horticultural lighting, street lighting, torch forvideo, general illumination (e.g., home, shop, office and studiolighting, theater/stage lighting and architectural lighting), augmentedreality (AR) lighting, virtual reality (VR) lighting, as back lights fordisplays, and IR spectroscopy. A single LED may provide light that isless bright than an incandescent light source, and, therefore,multi-junction devices or arrays of LEDs (such as monolithic LED arrays,micro LED arrays, etc.) may be used for applications where morebrightness is desired or required.

The present disclosure generally relates manufacture of micro lightemitting diode (uLED) displays and of multi-wavelength light emitterswith large bandwidth for free-space visible light communications.Epitaxial tunnel junctions may be used to combine multiple emissionwavelengths within a single LED device

Manufacturing uLEDs could be simplified if two or more active regionsemitting different wavelengths may be integrated within a single wafer.Such an approach may be possible within the AlInGaN materials systemsince it has been demonstrated that blue, green and red LEDs can be allmade in this system. However, use of a multi-color chip in a uLEDdisplay requires not only stacking multiple layers able to emit atdifferent wavelengths within a single epitaxial growth run, but alsorequires an ability to change respective emission intensity ratiosbetween the emitters of different wavelengths.

One possible way to make a multicolor uLED chip may be to form multiplequantum wells (MQW) able to emit red, green, and blue light within asingle active region, i.e. between the p- and n-layers of one p-njunction. With an optimized growth order of the multiple quantum wells,an LED with one predominant color that can be changed depending on thedriving current, e.g., it may appear predominantly red at low current,predominantly green at intermediate current, and predominantly blue athigh current. However, this type of color control mechanism makes itdifficult to adjust the surface radiance and dominant wavelength of theLED independently of each other, and consequent color purity can bepoor.

As an alternative, two or more pixels of different wavelengths in thesame device footprint can be formed by growing an LED of several p-njunctions within the same epitaxial wafer. A multi-level mesa etchingprocedure can be executed to make independent electrical contacts toeach of the p-n junctions. One or more emitter layers of differentwavelengths can be embedded in separate p-n junctions with separatecurrent paths so the wavelength and radiance can be controlledindependently. Unfortunately, given current post-epitaxial deviceprocessing limitations it may be difficult to manufacture such multiplewavelength uLEDs. Dry etching may be usually needed to open vias forcontacting buried layers. The dry etch process introduces atomic-leveldamage to the crystal that changes its conductivity type from p-type ton-type. Due to this conductivity type conversion it may not be possibleto obtain an ohmic contact of low resistance to a buried p-type nitridesurface that has been exposed by dry etching. In effect, creating anon-ohmic contact to an etched p-GaN surface can result in a forwardvoltage penalty of one volt or more for some of the active regions. Sucha large forward voltage may not be considered practical with respect tothe power consumption requirements of micro-displays.

In accordance with other embodiments of the invention, a multiplequantum well LED suitable for wafer-scale uLEDs can include a first LEDincluding a group of quantum wells able to emit light of a firstwavelength. A second LED including a group of quantum wells may also beformed, with the second LED able to emit light of a second wavelengthdistinct from the wavelength emitted by the first LED. A tunnel junctionlayer may be formed to separate the first and second LEDs. The quantumwells in the LEDs may be caused to emit light injecting current fromindependent electrical contacts that extend to each of the first andsecond LEDs. In some embodiments, three or more LEDs can be defined toallow for RGB uLEDs.

In another embodiment, a method of manufacturing a multiple quantum wellLED includes forming a first LED including a group of quantum wells on asubstrate. A tunnel junction layer may be formed on the first LED, and asecond LED may be formed on the tunnel junction layer. At least onechannel with sidewalls may be etched through the first LED to define atleast two light emission regions in the multiple quantum well LED. Metalcontacts can be applied to provide independent electrical contacts toeach of the first and second groups of quantum wells. The p-GaN layerscan be activated, at least in part, after an anneal promoting hydrogendiffusion through the sidewall of an etch channel. In some embodiments,the channel with sidewalls may be etched through to the substrate, whilein other embodiments etching only proceeds to a n-GaN layer positionedon the substrate.

FIG. 1A illustrates multiple LEDs formed on a substrate that may be usedto form an LED. The LED may have multiple quantum wells, multipledefined channels separating the LED into different pixels, and/ordiscrete wavelength emitter sites for visual light communication (VLC).The uLED device may include a mesa structure and independent electricalcontacts.

In the following description, it will be understood that the terms lightemission, color, red/green/blue, and RGB may include any light mostlycomposed of, centered upon, or predominantly having a specifiedwavelength. In some embodiments, light emission may also includenon-visible light, including near IR and UV light. In other embodiments,multiple quantum wells can support closely matched but still distinctemission wavelengths (e.g., independently modulated dual blue emittershaving respective 430 nm and 460 nm peak wavelengths).

Referring now to FIG. 1A, a multiple quantum well LED may include asubstrate 106 which may be formed from patterned or unpatternedsapphire. In some embodiments the substrate 106 may be polished and usedto form at least a portion of a display. The substrate 106 may supportlight emitting LEDs that can include multiple p and n-layers sandwichingone or more groups of quantum wells, with at least some of the quantumwells forming active regions capable of light emission. For example, thesubstrate 106 may support a first group of quantum wells positionedbetween n-GaN and p-GaN layers to form a first LED 101 able to emitlight of a first wavelength (e.g., blue). A second group of quantumwells may be positioned between n-GaN and p-GaN layers to form a secondLED 103 able to emit light of a second wavelength (e.g., green) distinctfrom the first wavelength, with a first tunnel junction 102 separatingthe first LED 101 and the second LED 103. A second tunnel junction layer104 may be formed on the second LED 103 and a third group of quantumwells may be positioned between n-GaN and p-GaN layers to form a thirdLED 105 able to emit light of a third wavelength (e.g., red) distinctfrom the first and second wavelengths. As described below, independentelectrical contacts may be formed as contact pairs to provide sufficientvoltage and current to induce light emission from each of the first LED101, the second LED 103, and the third LED 105 from a suitable printedcircuit board. In some embodiments, each of the first LED 101, thesecond LED 103, and the third LED 105 may be independently voltagebiased.

Advantageously, as compared to a uLED display made from conventionalsingle-wavelength uLEDs, the number of epitaxial growth runs required toproduce source die for uLED displays may be reduced to one third (or onehalf if stacking only two wavelengths) of the number or runs requiredwith existing methods, reducing cost and improving throughput at the epimanufacturing stage. In addition, the number of pick and placeoperations required to populate a display may be halved or cut to athird, since two or three pixels may be transferrable in each pick andplace operation.

For even more efficient manufacture, in wafer scale embodiments thatallow for all required wavelengths to be efficiently grown on one epiwafer, there may be no required pick and place. The display uLEDs canremain on a continuous polished sapphire support/substrate that can forma part of the packaging of the uLED display.

As another advantage, since all contacts to buried layers can be made ton-GaN surfaces, the disclosed structures and methods avoid problemsassociated with making an ohmic electrical contact to etched p-GaNsurfaces, making possible lower operating voltage and higher wall-plugefficiency. The number of etching steps to make all necessary electricalcontacts may be also reduced, and restrictions on control of the etchingrate may be relaxed since all etched contacts in the tunnel junctioninvention may be made to thick n-GaN layers (versus generally thinnerp-GaN layers), even while maintaining high LED efficiency.

As seen in FIG. 1A, multiple LEDs of quantum wells capable of lightemission of various wavelengths may be formed on a substrate 106. Thesubstrate 106 may be capable of supporting epitaxial III-nitride filmgrowth. The substrate 106 may compose, for example, sapphire, patternedsapphire, or silicon carbide. A first LED 101 may be formed on thesubstrate 106. The first LED may compose any Group III-V semiconductors,including binary, ternary, and quaternary alloys of gallium, aluminum,indium, and nitrogen, also referred to as III-nitride materials. In anexample, the first LED 101 may compose GaN. The first LED 101 may beformed using conventional deposition techniques, such as metal-organicchemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), orother epitaxial techniques. In an epitaxial deposition process, chemicalreactants provided by one or more source gases may be controlled and thesystem parameters may be set so that depositing atoms arrive at adeposition surface with sufficient energy to move around on the surfaceand orient themselves to the crystal arrangement of the atoms of thedeposition surface. Accordingly, the first LED 101 may be grown on thesubstrate 106 using conventional epitaxial techniques.

The first LED 101 may be formed from any applicable material to emitphotons when excited. More specifically the first LED 101 may be formedfrom III-V semiconductors including, but not limited to, AlN, AIP, AIAs,AISb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, II-VI semiconductorsincluding, but not limited to, ZnS, ZnSe, CdSe, CdTe, group IVsemiconductors including, but not limited to Ge, Si, SiC, and mixturesor alloys thereof.

The first LED 101 may include a first semiconductor layer 107, an activeregion 108 on the first semiconductor layer 107, and a secondsemiconductor layer 109 on the active region 108. The firstsemiconductor layer 107 may be an n-type layer and one or more layers ofsemiconductor material that include different compositions and dopantconcentrations including, for example, preparation layers, such asbuffer or nucleation layers, and/or layers designed to facilitateremoval of the growth substrate. These layers may be n-type or notintentionally doped, or may even be p-type device layers. The layers maybe designed for particular optical, material, or electrical propertiesdesirable for the light emitting region to efficiently emit light. Theactive region 108 may be between the first semiconductor layer 107 andthe second semiconductor layer 109 and may receive a current such thatthe active region 108 emits light beams. The second semiconductor layer109 may be a p-type layer and may include multiple layers of differentcomposition, thickness, and dopant concentrations, including layers thatmay not be intentionally doped, or n-type layers. An electrical currentmay be caused to flow through the p-n junction (e.g., via contacts) inthe active region 108 and the active region 108 may generate light of afirst wavelength determined at least in part by the bandgap energy ofthe materials. The first LED 101 may include one more quantum wells.

A first tunnel junction 102 may be formed on the first LED 101. Thefirst tunnel junction 102 may be a barrier layer, such as a thininsulating layer or electric potential. The first tunnel junction may bebetween two electrically conducting materials. Electrons (orquasiparticles) may pass through the first tunnel junction 102 by theprocess of quantum tunneling. The first tunnel junction 102 may beformed using conventional deposition techniques, such as MOCVD), MBE, orother epitaxial techniques.

A second LED 103 may be formed on the first tunnel junction 102. Thesecond LED 103 may be similar to the first LED 101 and may be composedof similar layers. The second LED 103 may be formed using similartechniques as those described above with reference to the first LED 101.

A second tunnel junction 104 may be formed on the second LED 103. Thesecond tunnel junction 104 may be similar to the first tunnel junctionand may be composed of similar layers. The second tunnel junction 104may be formed using similar techniques as those described above withreference to the first tunnel junction 102.

A third LED 105 may be formed on the second tunnel junction 104. Thethird LED 105 may be similar to the first LED 101 and may be composed ofsimilar layers. The third LED 105 may be formed using similar techniquesas those described above with reference to the first LED 101.

The first semiconductor layer 107, the active region 108, and the thirdsemiconductor layer 109 of each LED may be composed of differentmaterials, such that one or more of the first LED 101, the second LED103, and the third LED 105 emit a light of a different wavelength. Forexample, the first LED 101, the second LED 103, and the third LED 105may emit different red, green, and blue light. In another example, thefirst LED 101, the second LED 103, and the third LED 105 may emit lightof different wavelengths (e.g., separated by approximately 10-30 nm)within a specific color range (e.g., 420-480 nm).

While any order of arranging different LEDs may be possible, in oneembodiment a LED having an active region that emits the shortestwavelength may be the first one grown in the sequence. This arrangementmay avoid or minimize internal absorption of the blue emission by theactive regions of longer wavelengths.

Epitaxial growth conditions can be similar to those required for aconventional blue LED growth run using patterned or non-patternedsapphire substrates. After completing sequential growth of a n-GaNlayer, blue-emitting multiple quantum wells, and a p-GaN layer thatcollectively form the LED 101 capable of emitting blue light, growthconditions may be changed to grow the first tunnel junction 102.

After formation of the first tunnel junction 102, the second LED 103capable of emitting green light may be formed. The second LED 103 may bealso grown in a manner similar to that of a conventional green LED. Thethickness and/or growth conditions of an n-contact layer may be furthermodified. After completing the second semiconductor layer 109 of thesecond LED 103, a second tunnel junction 104 may be grown.

The third LED 105 may be a red light emitting InGaN LED. Growth of thethird LED 105 may be similar to that of a conventional red LED, but thethickness and/or growth conditions of an n-contact layer can be furthermodified.

As will be appreciated, various designs for the first tunnel junction102 and the second tunnel junction 104 or LED active regions can beused. The first tunnel junction 102 and the second tunnel junction 104may aid in lateral current spreading, and may include any layer ofdifferent Group III elemental composition and/or different dopingconcentration to both the first semiconductor layer 107 and the secondsemiconductor layer 109. The first tunnel junction 102 and the secondtunnel junction 104 may utilize polarization dipoles which naturallyoccur at interfaces between nitride layers of different Group IIIelemental compositions. The first tunnel junction 102 and the secondtunnel junction 104 may be created by forming layers of low resistancep-type confinement in conjunction with various impurities able togenerate mid gap states.

Referring now to FIG. 1B, the first LED 101, the second LED 103, and thethird LED 105, each having multiple quantum wells, and the first tunneljunction 102 and the second tunnel junction 104 may be etched. Theetching may include conventional photolithography and dry etch processesto define one or more channels. A first channel 111 may define a firstpixel 113 and a second pixel 114. A second channel 112 may define thesecond pixel 114 and a third pixel 115.

Conventional dry etching processes may be used, but various combinationsof masks and etch depths may be required. The conventional photoresistexposure, develop, strip and clean steps may be understood in the artand have been omitted from the figure. Layers of a conventionalphotoresist 116 may be formed on the first pixel 113, the second pixel114, and the third pixel 115.

The first channel 111 and the second channel 112 may be formed byleaving portions of the LEDs unmasked during the etching. A deep etchdown to the substrate 106 may be desired for these locations. A firstetching process may effectively stop on the sapphire due to its veryslow etching rate relative to epitaxial layers of the LEDs.

A surface of the first semiconductor layer 107 in the first LED 101 maybe left during the etching process to serves as an n-contact 110 for thefirst pixel.

Referring now to FIG. 1C, different portions of the first LED 101, thefirst tunnel junction 102, the second LED 103, the second tunneljunction 104, and the third LED 105 may be removed in a second etchingprocess to further define the different pixels.

Each of the first channel 111 and the second channel 112 may be extendedto expose the substrate 106. The first pixel 113 may be etched to exposean upper surface 117 of the first semiconductor layer 107 in the secondLED 103. The surface 117 may serve as a p-type contact for the firstpixel 113 The second pixel 114 may be etched to expose the upper surface117 of the first semiconductor layer 107 in the second LED 103 as well.The surface 118 may serve as an n-type contact for the second pixel 114.

Referring now to FIG. 1D, a third etching step may be performed tofurther define the pixels. The second pixel 114 may be etched to exposean upper surface 119 of the first semiconductor layer 107 in the thirdLED 105. The surface 119 may serve as a p-type contact for the secondpixel 114.

The third pixel 115 may be etched to expose the upper surface 120 of thefirst semiconductor layer 107 in the third LED 105. The surface 120 mayserve as an n-type contact for the third pixel 115. The unetched secondsemiconductor layer 109 in the third LED 105 may serve as an n-contact120 for the third pixel 115. In effect, etches to the p-contact for thefirst pixel 113 and the second pixel 114 may remove light absorbinglayers for those pixels (e.g., green and red LEDs may absorb lightemitted from a blue LED).

It should be noted that the first pixel 113, the second pixel 114, andthe third pixel 115 may be formed in any combination and in anyconfiguration. For example, more than one of the first pixel 113, thesecond pixel 114, and the third pixel 115 may be adjacent to oneanother. In addition, the first pixel 113, the second pixel 114, and thethird pixel 115 may be arranged such that the first pixel 113 isadjacent to the third pixel 115. In addition, a device may be formedthat includes one type of pixel, two types of pixels, or all three typesof pixels. In addition, the number of LEDs and tunnel junctionsdescribed above is not meant to be limiting.

In an example, p-GaN activation may be accomplished by facilitatinglateral diffusion of hydrogen through sidewalls of the etched channels,an anneal can be done following photoresist strip and cleaning (i.e.after completion of the third dry etch shown in FIG. 1D). It may beadvantageous to anneal at this time, rather than earlier in the process,because the defined channels between the pixels may provide an efficientpath for lateral diffusion and escape of hydrogen from the p-GaN layers.Activation anneal process conditions promoting hydrogen diffusion may besimilar to, or different from, those of a conventional LED and nospecial annealing conditions may be claimed here. Alternatively,epitaxial processes with minimal hydrogen (e.g., MBE or RPCVD) could beused for growing the tunnel junctions and an anneal to remove hydrogenby lateral diffusion would not be required.

After the p-GaN activation anneal, various additive processing steps maybe needed to define electrical connections to the pixels.

As seen in FIG. 1E, a conformal dielectric layer 122 may be formed onthe first pixel 113, the second pixel 114, and the third pixel 115. Theconformal dielectric layer 122 may be formed using a conventionaldeposition process, such as plasma-enhanced chemical vapor deposition.The conformal dielectric layer 122 may compose dielectric material suchas silicon dioxide. The conformal dielectric layer 122 may be formed Theelectrically insulating conformal dielectric layer 122 may passivatemesa sidewalls and isolate from each other the metal contact pads thatwill be deposited in later process steps.

Referring now to FIG. 1F, openings may be formed in the conformaldielectric layer 122. Portions of the conformal dielectric layer 122 maybe masked with the resist 116 as shown above with reference to FIG. 1Dand portions may remain exposed. The exposed portions may be removedusing a conventional etching process, such as dry action. A firstopening 123 may be formed on the first pixel 113 to expose the firstsemiconductor layer 107 of the first LED 101. A second opening 124 maybe formed on the first pixel 113 to expose the first semiconductor layer107 of the second LED 103. A third opening 125 may be formed on thesecond pixel 114 to expose the first semiconductor layer 107 of thesecond LED 103. A fourth opening 126 may be formed on the second pixel114 to expose the first semiconductor layer 107 of the third LED 105. Afifth opening 127 may be formed on the third pixel 115 to expose thefirst semiconductor layer 107 of the third LED 105. A sixth opening 128may be formed on the third pixel 115 to expose the second semiconductorlayer 109 of the third LED 105.

Referring now to FIG. 1G, a metal, for example an aluminum/gold bilayermay be evaporated for metallization and patterned by lift-off to formone or more of a first contact 129 a, a second contact 129 b, a thirdcontact 129 c, a fourth contact 129 c, and fifth contact 129 d. Thelift-off mask openings may coincide with openings in the dielectric asshown in FIG. 1G. The first contact 129 a may be formed in the firstopening 123 and may be on the first semiconductor layer 107 of the firstLED 101. The first contact 129 a may be an n-type contact for the firstpixel 113. The second contact 129 b may be formed in the second opening124 and may be on the first semiconductor layer 107 of the second LED103 in the first pixel 113. The second contact 129 b may be a p-typecontact for the first pixel 113.

The third contact 129 c may be formed in the third opening 125 and maybe on the first semiconductor layer 107 of the second LED 103 in thesecond pixel 114. The third contact 129 c may be an n-type contact forthe second pixel 114. The fourth contact 129 d may be formed in thefourth opening 126 and may be on the first semiconductor layer 107 ofthe third LED 105 in the second pixel 114. The fourth contact 129 d maybe a p-type contact for the second pixel 114.

The fifth contact 129 d may be formed in the fifth opening 127 and maybe on the first semiconductor layer 107 of the third LED 105 in thethird pixel 115. The fifth contact 129 d may be an n-type contact forthe third pixel 115.

As shown in FIG. 1H, a sixth contact 130 may be formed in the sixthopening 128 on the third pixel 115 using a metallization process. Thesixth contact 130 may compose silver and may be similarly evaporated andpatterned onto the second semiconductor layer 109 of the third LED 105to form an LED array 121 as shown in FIG. 1H.

As seen with respect to FIG. 1I, after wafer singulation, the LED array121 may be attached to a LED device attach region 318, as described infurther detail below. In an example, the LED device attach region 318may be a complementary metal oxide semiconductor (CMOS) integratedcircuit (IC) array having metal interconnect bonding corresponding tothe contacts formed on the LED array 121. A first surface of the LEDdevice attach region 318 may have one or more interconnect bumpscorresponding to the contacts on the pixels. The interconnect bumps mayhave different heights defined to match the first pixel 113, the secondpixel 114, and the third pixel 115, allowing use of substantially samesize interconnect bonding structures. In other variations, the firstsurface of the LED device attach region 318 may be substantially flat,and interposers or connecting pillars of differing height can be used.Driver circuitry as described below with FIG. 4B may be coupled to theLED device attach region 318 to allow each contact pair of the firstpixel 113, the second pixel 114, and the third pixel 115 to be biasedindependently at a desired voltage. For example, the driver circuitrymay include a driver configured to provide a first driving current to afirst pair of electrodes 152 coupled to the first pair of contacts (129a and 129 b), a second pair of electrodes 154 coupled to the second pairof contacts (129 c and 129 d), and a third pair of electrodes 156coupled to the third pair of contacts (129 e and 130).

For example, the LED device attach region 318 may be configured toprovide a voltage to only the first contact 129 a and the second contact129 b of the first pixel 113 (collectively referred to as a first pairof contacts), a voltage to only the third contact 129 c and the fourthcontact 129 d of the second pixel 114 (collectively referred to as asecond pair of contacts), and a voltage to only the fifth contact 129 eand the sixth contact 130 of the third pixel 115 (collectively referredto as a third pair of contacts). The LED device attach region 318 may beconfigured to provide voltages in any combination of those describedabove. The LED device attach region 318 may be coupled to the LED deviceattach region 318 described below with reference to FIG. 3 .

Light of a first wavelength be emitted from the first pixel 113, lightof a second wavelength may be emitted from the second pixel 114, andlight of a third wavelength may be emitted from the third pixel throughthe substrate 106.

Referring now to FIG. 1J, another example of an LED array 138 is shown.The LED array 138 may be formed using the same or similar epitaxialgrowth processes and wafer processing steps as described above, butusing a different mask set to etch the different layers. The masks usedfor this embodiment may be modified to prevent etching of a channel downto the substrate 106.

The channels 136, 137, and 139 may be masked for all etching steps, butmay be left unmasked for the metal deposition steps described above.This may result in an LED array 138 having a first common electrode 132that may be used for the p-contact of the first pixel 113 and then-contact of the second pixel 114 and a second common electrode 133 thatmay be used for the p-contact of the second pixel 114 and the n-contactof the third pixel 115. It may be possible to generateelectroluminescence from any one of the individual active regions or anycombination thereof (including all three) by applying appropriate biasto the driving electrodes 132, 133, or 135 relative to a groundelectrode 134. For example, the driving voltage may be a combination of3/6/9V that results in the illumination of the first pixel 113, thesecond pixel 114, and the third pixel 115 together. A combination of3/3/6V may result in the illumination of the third pixel 115 and thefirst pixel 113 without passing any current through the second pixel114.

While potentially requiring greater voltages when the first LED 101, thesecond LED 103, and the third LED 105 may be simultaneously emittinglight, the LED array 138 may support higher pixel resolution due toreduction of overall footprint of the LED array 138 (i.e., a single uLEDmay produce all wavelengths which previously required 3 uLEDs toproduce). The smaller footprint may be a result of the smaller requiredelectrical contact area, and the lack of isolating gaps between thepixels of separate wavelengths. Complexity of the printed circuit boardmay also be reduced.

To support an ever-increasing volume of data traffic transmitted usingwireless communications, development of Gbit/sec class communicationsystems is necessary. However, there is currently insufficient availableradio spectrum to develop radio-frequency wireless systems with speedsin the Gbit/sec range. One alternative to radio-frequency wireless isprovided by visible light communications (VLC) that use wavelengths inthe visible region of the spectrum. VLC is a data communications variantwhich uses visible light between 140 and 800 THz (780-375 nm). VLC is asubset of optical wireless communications technologies. VLC may usefluorescent lamps (e.g., ordinary lamps, not special communicationsdevices) to transmit signals at 10 kbit/s, or LEDs for up to 112 Mbit/sover short distances. Systems may be able to transmit at full Ethernetspeed (10 Mbit/s) over distances of 1-2 kilometres (0.6-1.2 mi).

Specially designed electronic devices generally containing a photodiodemay receive signals from light sources, although in some casesconventional cell phone cameras or digital cameras may be sufficient.The image sensor used in these devices may be an array of photodiodes(i.e., pixels) and in some applications, the use of LED arrays may bepreferred over a single photodiode. Such a sensor may provide eithermulti-channel (e.g., 1 pixel=1 channel) or a spatial awareness ofmultiple light sources.

VLC may potentially provide on the order of THz/sec of unlicensedbandwidth, support a high degree of spatial reuse, and allow for highersecurity due to inherent difficulties in intercepting. Furthermore, VLCcan use existing infrastructure designed for illumination which can makepossible an additional wireless transmission capacity with comparativelysmall capital investment.

The data transmission rates possible with conventionalphosphor-converted white LEDs may be generally limited to under 100 MBpsdue to the slow temporal response of the phosphor among other factors.On the other hand, a white light source that mixes wavelengths emittedfrom two or more independently modulated LED sources has increasedbandwidth and is capable of data transmission rates up to 5 GBps.

A white light source comprised of three separate blue, green, and redLED chips could satisfy the requirements for both illumination and highbandwidth VLC applications. Alternatively, multiple blue chips (eachwith a phosphor to make white light) with peak wavelengths (WLs)differing by 20 nm or more could be put into a single package toincrease bandwidth with filters used on each detector to preventcross-talk between the different blue sources. Unfortunately for boththese alternatives, the significant amount of space required forassembly of multiple separate chips prevents design of compact, highlydirectional VLC systems.

The devices described above may support VLC applications. The firstcontact 129 a, the second contact 129 b, the third contact 129 c, thefourth contact 129 c, the fifth contact 129 d, and the sixth contact 130may be independently drivable to define light emission from each of thefirst pixel 113, the second pixel, 114, and the third pixel 115 tosupport VLC protocols.

Referring now to FIG. 1K, a diagram illustrating a combined display andVLC system 140 is illustrated. A smartphone 402 having a display 141,VLC emitter 142, and VLC receiver 143 (shown as not to scale magnifiedcartoon) may be used to interact with other devices such as ceilingmounted LED light 144 or another smartphone 145 that support VLCprotocols such as Li-Fi.

The VLC emitter 142 may also be capable of acting as a display, but thedisplay and VLC functionality may be separate. The VLC emitter 142 mayinclude the LED array 121 and the LED array 138 described above.

The VLC receiver 143 may include an avalanche photodiode, or when moresensitive operation is required, a single photon avalanche diode (SPAD).The smartphone 402 may include circuitry to convert data needingtransmission into a suitable driving modulation of the selected VLCemitters. The smartphone 402 may also include circuitry to convertreceived light modulations from the VLC receiver into available data.The VLC receiver 143 may be the sensor module 314 described below withreference to FIG. 3 .

Referring now to FIG. 1L, a diagram illustrating the VLC receiver 143 isshown. The VLC receiver 143 may include an amplification circuit 149 andan optical filter and optical concentrators 146. Beam divergence mayoccur in LEDs due to illuminating large areas results in attenuation.The optical concentrator 146 may be used to compensate this type ofattenuation. In addition, VLC may be vulnerable to interference fromother sources such as sunlight and other illumination. Therefore, theoptical filters 146 may be used mitigate the DC noise components presentin the received signal.

In the VLC receiver 143, light may be detected using a photodiode 147and may be converted to photo current. The photodiode may include one ormore of a silicon photodiode, a PIN diode, and avalanche photodiode. Thephotodiode 451 may include one or more of the first pixel 113, thesecond pixel 114, and the third pixel 115. The photo current may bereceived by a clock and data recovery (CDR) unit 148. The CDR unit 148may provide an output to one or more circuits in the VLC system 140.

Light may pass through optical filter and optical concentrators 146 andbe detected by the photodiode 147. The amplification circuit 149 mayamplify the signal and provide it to the CDR unit 148, which may decodeand process the signal.

Independent electrical connections may be made to the first pixel 113,the second pixel 114, and the third pixel 115 to allow for high speedlight intensity modulation and data transfer using IEEE 802.15.7 orother suitable wireless protocols. Since multiple wavelengths may besupported, improved protocols based on optical orthogonalfrequency-division multiplexing (O-OFDM) modulation may be used. A VLCsignal may be directed to an LED array having stacked active regionsemitting light of different wavelength. Each pixel may emit differentwavelengths or alternatively, each pixel can emit more than onewavelength.

Use of a multiple wavelength system such as the LED array 121 and theLED array 138 may deliver connections having a data transfer rate up toabout 5 Gbps, comparing favorably to phosphor coated white LEDs onlyable deliver up to about 100 Mbps.

Color shift keying (CSK), outlined in IEEE 802.15.7, is an intensitymodulation based modulation scheme for VLC. CSK is intensity-based, asthe modulated signal takes on an instantaneous color equal to thephysical sum of three RGB LED instantaneous intensities. This modulatedsignal jumps instantaneously, from symbol to symbol, across differentvisible colors. Accordingly, CSK may be construed as a form of frequencyshifting. However, this instantaneous variation in the transmitted colormay not be humanly perceptible, because of the limited temporalsensitivity in the human vision. A critical flicker fusion threshold(CFF) and a critical color fusion threshold (CCF), may limit humans fromresolving temporal changes shorter than 0.01 second. Transmissions fromthe LED array 121 and the LED array 138 may be preset to time-average(over the CFF and the CCF) to a specific time-constant color. Humans mayperceive only the preset color that seems constant over time, but cannotperceive the instantaneous color that varies rapidly in time. In otherwords, CSK transmission may maintain a constant time-averaged luminousflux, even as its symbol sequence varies rapidly in chromaticity.

Referring now to FIG. 1M, a flowchart illustrating a method for use ofan LED array is shown. In step 180, a first voltage may be provided to afirst pixel of the LED array. In step 182, a second voltage may beprovided to a second pixel of the LED array. The first pixel and thesecond pixel may be separated by a first trench extending to asubstrate. In step 184, a third voltage may be provided to a third pixelof the LED array. The second pixel and the third pixel may be separatedby a second trench extending to the substrate.

Referring now to FIG. 1N, a flowchart illustrating a method of forming adevice is shown. In step 190, one or more LEDs and one or more tunneljunctions may be formed on a substrate. In step 192, a first trench maybe formed through the one or more tunnel junctions and the one or moreLEDs to define a first pixel and a second pixel. The first trench mayextend to the substrate. In an optional step 194, a second trench may beformed through the one or more tunnel junctions and the one or more LEDsto define the second pixel and a third pixel.

A device may include a first light emitting diode (LED) on a firstsurface of a substrate, a first tunnel junction on the first LED a firstsemiconductor layer on the first tunnel junction, and a conformaldielectric layer on at least a sidewall of the LED and the first surfaceof the substrate.

The device may include a first contact on a layer of the first LED and asecond contact on the first semiconductor layer.

The device may include a second LED on the first tunnel junction, thesecond LED comprising the first semiconductor layer, a second tunneljunction on the second LED, and a second semiconductor layer on thesecond tunnel junction.

The device may include a third contact on a layer of the second LED anda fourth contact on the second semiconductor layer.

The device may include a third LED on the second tunnel junction, thethird LED comprising the second semiconductor layer

The device may include a fifth contact on a first layer of the third LEDand a sixth contact on a second layer of the third LED.

The device may include the conformal dielectric layer on the firsttunnel junction, the second LED, the second tunnel junction, and thethird LED.

A LED array may include a first pixel and a second pixel on a substrate,the first pixel and the second pixel comprising one or more tunneljunctions on one or more LEDs, and a first trench between the firstpixel and the second pixel, the trench extending to the substrate.

The first pixel may comprise a first LED on the substrate, a firsttunnel junction on the first LED, and a first semiconductor layer on thetunnel junction.

The LED array may include a first contact on a layer of the first LEDand a second contact on the first semiconductor layer.

The second pixel may include a first LED on the substrate, a firsttunnel junction on the first LED, a second LED on the first tunneljunction, a second tunnel junction of the second LED, and a secondsemiconductor layer on the second tunnel junction.

The LED array may include a second contact on a layer of the second LED,and a second contact on the second semiconductor layer.

The LED array may include a third pixel on the substrate, the thirdpixel comprising one or more tunnel junctions formed on one or moreLEDs, a second trench between the second pixel and the third pixel, thetrench extending to the substrate.

The third pixel may include a first LED on the substrate, a first tunneljunction on the first LED, a second LED on the first tunnel junction, asecond tunnel junction on the second LED, and a third LED on the secondtunnel junction.

The LED array may include a fifth contact on a first layer of the thirdLED and a sixth contact on a second layer of the third LED.

A method may include forming one or more LEDs and one or more tunneljunctions on a substrate and forming a first trench through the one ormore tunnel junctions and the one or more LEDs to define a first pixeland a second pixel, the first trench extending to the substrate.

The first pixel may include a first LED on the substrate, a first tunneljunction on the first LED, a first semiconductor layer on the tunneljunction.

The second pixel may include a first LED on the substrate, a firsttunnel junction on the first LED, a second LED on the first tunneljunction, a second tunnel junction of the second LED, and a secondsemiconductor layer on the second tunnel junction.

The method may include forming a second trench through the one or moretunnel junctions and the one or more LEDs to define the second pixel anda third pixel, the second trench extending to the substrate.

The third pixel may include a first LED on the substrate, a first tunneljunction on the first LED, a second LED on the first tunnel junction, asecond tunnel junction on the second LED, and a third LED on the secondtunnel junction.

FIG. 2A is a diagram of an LED device 200 in an example embodiment.

The LED device 200 may include a substrate 202, an active layer 204, awavelength converting layer 206, and primary optic 208. In otherembodiments, an LED device may not include a wavelength converter layerand/or primary optics.

As shown in FIG. 2A, the active layer 204 may be adjacent to thesubstrate 202 and emits light when excited. Suitable materials used toform the substrate 202 and the active layer 204 include sapphire, SiC,GaN, Silicone and may more specifically be formed from a III-Vsemiconductors including, but not limited to, AlN, AIP, AIAs, AISb, GaN,GaP, GaAs, GaSb, InN, InP, InAs, InSb, II-VI semiconductors including,but not limited to, ZnS, ZnSe, CdSe, CdTe, group IV semiconductorsincluding, but not limited to Ge, Si, SiC, and mixtures or alloysthereof.

The wavelength converting layer 206 may be remote from, proximal to, ordirectly above active layer 204. The active layer 204 emits light intothe wavelength converting layer 206. The wavelength converting layer 206acts to further modify wavelength of the emitted light by the activelayer 204. LED devices that include a wavelength converting layer areoften referred to as phosphor converted LEDs (“PCLED”). The wavelengthconverting layer 206 may include any luminescent material, such as, forexample, phosphor particles in a transparent or translucent binder ormatrix, or a ceramic phosphor element, which absorbs light of onewavelength and emits light of a different wavelength.

The primary optic 208 may be on or over one or more layers of the LEDdevice 200 and allow light to pass from the active layer 204 and/or thewavelength converting layer 206 through the primary optic 208. Theprimary optic 208 may be a lens or encapsulate configured to protect theone or more layers and to, at least in part, shape the output of the LEDdevice 200. Primary optic 208 may include transparent and/orsemi-transparent material. In example embodiments, light via the primaryoptic may be emitted based on a Lambertian distribution pattern. It willbe understood that one or more properties of the primary optic 208 maybe modified to produce a light distribution pattern that is differentthan the Lambertian distribution pattern.

FIG. 2B shows a cross-sectional view of a lighting system 220 includingan LED array 210 with pixels 201A, 201B, and 201C, as well as secondaryoptics 212 in an example embodiment. The LED array 210 includes pixels201A, 201B, and 201C each including a respective wavelength convertinglayer 206B active layer 204B and a substrate 202B. The LED array 210 maybe a monolithic LED array manufactured using wafer level processingtechniques, a micro LED with sub-500 micron dimensions, or the like.Pixels 201A, 201B, and 201C, in the LED array 210 may be formed usingarray segmentation, or alternatively using pick and place techniques.

The spaces 203 shown between one or more pixels 201A, 201B, and 201C ofthe LED devices 200B may include an air gap or may be filled by amaterial such as a metal material which may be a contact (e.g.,n-contact).

The secondary optics 212 may include one or both of the lens 209 andwaveguide 207. It will be understood that although secondary optics arediscussed in accordance with the example shown, in example embodiments,the secondary optics 212 may be used to spread the incoming light(diverging optics), or to gather incoming light into a collimated beam(collimating optics). In example embodiments, the waveguide 207 may be aconcentrator and may have any applicable shape to concentrate light suchas a parabolic shape, cone shape, beveled shape, or the like. Thewaveguide 207 may be coated with a dielectric material, a metallizationlayer, or the like used to reflect or redirect incident light. Inalternative embodiments, a lighting system may not include one or moreof the following: the wavelength converting layer 206B, the primaryoptics 208B, the waveguide 207 and the lens 209.

Lens 209 may be formed form any applicable transparent material such as,but not limited to SiC, aluminum oxide, diamond, or the like or acombination thereof. Lens 209 may be used to modify the a beam of lightinput into the lens 209 such that an output beam from the lens 209 willefficiently meet a desired photometric specification. Additionally, lens209 may serve one or more aesthetic purpose, such as by determining alit and/or unlit appearance of the p 201A, 201B and/or 201C of the LEDarray 210.

FIG. 3 is a top view of an electronics board 310 for an integrated LEDlighting system according to one embodiment. In alternative embodiments,two or more electronics boards may be used for the LED lighting system.For example, the LED array may be on a separate electronics board, orthe sensor module may be on a separate electronics board. In theillustrated example, the electronics board 310 includes a power module312, a sensor module 314, a connectivity and control module 316 and anLED attach region 318 reserved for attachment of an LED array to asubstrate 320.

The substrate 320 may be any board capable of mechanically supporting,and providing electrical coupling to, electrical components, electroniccomponents and/or electronic modules using conductive connecters, suchas tracks, traces, pads, vias, and/or wires. The power module 312 mayinclude electrical and/or electronic elements. In an example embodiment,the power module 312 includes an AC/DC conversion circuit, a DC/DCconversion circuit, a dimming circuit, and an LED driver circuit.

The sensor module 314 may include sensors needed for an application inwhich the LED array is to be implemented.

The connectivity and control module 316 may include the systemmicrocontroller and any type of wired or wireless module configured toreceive a control input from an external device.

The term module, as used herein, may refer to electrical and/orelectronic components disposed on individual circuit boards that may besoldered to one or more electronics boards 310. The term module may,however, also refer to electrical and/or electronic components thatprovide similar functionality, but which may be individually soldered toone or more circuit boards in a same region or in different regions.

FIG. 4A is a top view of the electronics board 310 with an LED array 410attached to the substrate 320 at the LED device attach region 318 in oneembodiment. The electronics board 310 together with the LED array 410represents an LED system 400A. Additionally, the power module 312receives a voltage input at Vin 497 and control signals from theconnectivity and control module 316 over traces 418B, and provides drivesignals to the LED array 410 over traces 418A. The LED array 410 isturned on and off via the drive signals from the power module 312. Inthe embodiment shown in FIG. 4A, the connectivity and control module 316receives sensor signals from the sensor module 314 over trace 418C.

FIG. 4B illustrates one embodiment of a two channel integrated LEDlighting system with electronic components mounted on two surfaces of acircuit board 499. As shown in FIG. 4B, an LED lighting system 400Bincludes a first surface 445A having inputs to receive dimmer signalsand AC power signals and an AC/DC converter circuit 412 mounted on it.The LED system 400B includes a second surface 445B with the dimmerinterface circuit 415, DC-DC converter circuits 440A and 440B, aconnectivity and control module 416 (a wireless module in this example)having a microcontroller 472, and an LED array 410 mounted on it. TheLED array 410 is driven by two independent channels 411A and 411B. Inalternative embodiments, a single channel may be used to provide thedrive signals to an LED array, or any number of multiple channels may beused to provide the drive signals to an LED array.

The LED array 410 may include two groups of LED devices. In an exampleembodiment, the LED devices of group A are electrically coupled to afirst channel 411A and the LED devices of group B are electricallycoupled to a second channel 411B. Each of the two DC-DC converters 440Aand 440B may provide a respective drive current via single channels 411Aand 411B, respectively, for driving a respective group of LEDs A and Bin the LED array 410. The LEDs in one of the groups of LEDs may beconfigured to emit light having a different color point than the LEDs inthe second group of LEDs. Control of the composite color point of lightemitted by the LED array 410 may be tuned within a range by controllingthe current and/or duty cycle applied by the individual DC/DC convertercircuits 440A and 440B via a single channel 411A and 411B, respectively.Although the embodiment shown in FIG. 4B does not include a sensormodule (as described in FIG. 3 and FIG. 4A), an alternative embodimentmay include a sensor module.

The illustrated LED lighting system 400B is an integrated system inwhich the LED array 410 and the circuitry for operating the LED array410 are provided on a single electronics board. Connections betweenmodules on the same surface of the circuit board 499 may be electricallycoupled for exchanging, for example, voltages, currents, and controlsignals between modules, by surface or sub-surface interconnections,such as traces 431, 432, 433, 434 and 435 or metallizations (not shown).Connections between modules on opposite surfaces of the circuit board499 may be electrically coupled by through board interconnections, suchas vias and metallizations (not shown).

According to embodiments, LED systems may be provided where an LED arrayis on a separate electronics board from the driver and controlcircuitry. According to other embodiments, a LED system may have the LEDarray together with some of the electronics on an electronics boardseparate from the driver circuit. For example, an LED system may includea power conversion module and an LED module located on a separateelectronics board than the LED arrays.

According to embodiments, an LED system may include a multi-channel LEDdriver circuit. For example, an LED module may include embedded LEDcalibration and setting data and, for example, three groups of LEDs. Oneof ordinary skill in the art will recognize that any number of groups ofLEDs may be used consistent with one or more applications. IndividualLEDs within each group may be arranged in series or in parallel and thelight having different color points may be provided. For example, warmwhite light may be provided by a first group of LEDs, a cool white lightmay be provided by a second group of LEDs, and a neutral white light maybe provided by a third group.

FIG. 5 shows an example system 550 which includes an applicationplatform 560, LED systems 552 and 556, and secondary optics 554 and 558.The LED System 552 produces light beams 561 shown between arrows 561 aand 561 b. The LED System 556 may produce light beams 562 between arrows562 a and 562 b. In the embodiment shown in FIG. 5 , the light emittedfrom LED system 552 passes through secondary optics 554, and the lightemitted from the LED System 556 passes through secondary optics 558. Inalternative embodiments, the light beams 561 and 562 do not pass throughany secondary optics. The secondary optics may be or may include one ormore light guides. The one or more light guides may be edge lit or mayhave an interior opening that defines an interior edge of the lightguide. LED systems 552 and/or 556 may be inserted in the interioropenings of the one or more light guides such that they inject lightinto the interior edge (interior opening light guide) or exterior edge(edge lit light guide) of the one or more light guides. LEDs in LEDsystems 552 and/or 556 may be arranged around the circumference of abase that is part of the light guide. According to an implementation,the base may be thermally conductive. According to an implementation,the base may be coupled to a heat-dissipating element that is disposedover the light guide. The heat-dissipating element may be arranged toreceive heat generated by the LEDs via the thermally conductive base anddissipate the received heat. The one or more light guides may allowlight emitted by LED systems 552 and 556 to be shaped in a desiredmanner such as, for example, with a gradient, a chamfered distribution,a narrow distribution, a wide distribution, an angular distribution, orthe like.

In example embodiments, the system 550 may be a mobile phone of a cameraflash system, indoor residential or commercial lighting, outdoor lightsuch as street lighting, an automobile, a medical device, AR/VR devices,and robotic devices. The integrated LED lighting system shown in FIG. 3, LED System 400A shown in FIG. 4A, illustrate LED systems 552 and 556in example embodiments.

In example embodiments, the system 550 may be a mobile phone of a cameraflash system, indoor residential or commercial lighting, outdoor lightsuch as street lighting, an automobile, a medical device, AR/VR devices,and robotic devices. The LED System 400A shown in FIG. 4A and LED System400B shown in FIG. 4B illustrate LED systems 552 and 556 in exampleembodiments.

The application platform 560 may provide power to the LED systems 552and/or 556 via a power bus via line 565 or other applicable input, asdiscussed herein. Further, application platform 560 may provide inputsignals via line 565 for the operation of the LED system 552 and LEDsystem 556, which input may be based on a user input/preference, asensed reading, a pre-programmed or autonomously determined output, orthe like. One or more sensors may be internal or external to the housingof the application platform 560.

In various embodiments, application platform 560 sensors and/or LEDsystem 552 and/or 556 sensors may collect data such as visual data(e.g., LIDAR data, IR data, data collected via a camera, etc.), audiodata, distance based data, movement data, environmental data, or thelike or a combination thereof. The data may be related a physical itemor entity such as an object, an individual, a vehicle, etc. For example,sensing equipment may collect object proximity data for an ADAS/AV basedapplication, which may prioritize the detection and subsequent actionbased on the detection of a physical item or entity. The data may becollected based on emitting an optical signal by, for example, LEDsystem 552 and/or 556, such as an IR signal and collecting data based onthe emitted optical signal. The data may be collected by a differentcomponent than the component that emits the optical signal for the datacollection. Continuing the example, sensing equipment may be located onan automobile and may emit a beam using a vertical-cavitysurface-emitting laser (VCSEL). The one or more sensors may sense aresponse to the emitted beam or any other applicable input.

In example embodiment, application platform 560 may represent anautomobile and LED system 552 and LED system 556 may representautomobile headlights. In various embodiments, the system 550 mayrepresent an automobile with steerable light beams where LEDs may beselectively activated to provide steerable light. For example, an arrayof LEDs may be used to define or project a shape or pattern orilluminate only selected sections of a roadway. In an exampleembodiment, Infrared cameras or detector pixels within LED systems 552and/or 556 may be sensors that identify portions of a scene (roadway,pedestrian crossing, etc.) that require illumination.

Having described the embodiments in detail, those skilled in the artwill appreciate that, given the present description, modifications maybe made to the embodiments described herein without departing from thespirit of the inventive concept. Therefore, it is not intended that thescope of the invention be limited to the specific embodimentsillustrated and described.

What is claimed is:
 1. A light emitting diode (LED) array comprising: afirst pixel adjacent to a second pixel, the second pixel adjacent to athird pixel; the first pixel comprising a first stack and having a firstpair of contacts, the first pair of contacts comprising at least onefirst contact on a first pixel semiconductor layer, the first pixelsemiconductor layer on a first pixel tunnel junction, the first pixeltunnel junction on a first pixel LED on a substrate; a first trenchseparating the first pixel and the second pixel; and a second trenchseparating the third pixel and the second pixel, wherein the first pixelis configured to emit a light of a first wavelength, the second pixel isconfigured to emit a light of a second wavelength, and the third pixelis configured to emit a light of a third wavelength.
 2. The LED array ofclaim 1, wherein the second pixel comprises a second stack and has asecond pair of contacts, the second pair of contacts comprising at leastone second contact on a second pixel semiconductor layer, the secondpixel semiconductor layer on a second pixel second tunnel junction, thesecond pixel tunnel junction on a second pixel second LED, the secondpixel second LED on a second pixel first tunnel junction, the secondpixel first tunnel junction on a second pixel first LED on thesubstrate.
 3. The LED array of claim 2, wherein the third pixelcomprises a third stack and has a third pair of contacts, the third paidof contact comprising at least one third contact on a third pixel thirdLED, the third pixel third LED on a third pixel second tunnel junction,the third pixel second tunnel junction on a third pixel second LED, thethird pixel second LED on a third pixel first tunnel junction, the thirdpixel first tunnel junction on a third pixel first LED on the substrate.4. The LED array of claim 1, further comprising a dielectric layerformed over at least a portion of the first pixel, the second pixel, andthe third pixel.
 5. The LED array of claim 1, wherein the first pair ofcontacts are configured to receive a first voltage independent of thesecond pixel and the third pixel.
 6. The LED array of claim 2, whereinthe second pair of contacts are configured to receive a second voltageindependent of the first pixel and the third pixel.
 7. The LED array ofclaim 3, wherein the third pair contacts are configured to receive athird voltage independent of the first pixel and the second pixel. 8.The LED array of claim 4, wherein at least a portion of the dielectriclayer is conformal.
 9. The LED array of claim 3, wherein the first pairof contacts and the second pair of contacts comprises contacts to n-typesemiconductor, a first contact of the third pair of contacts comprises acontact to n-type semiconductor and a second contact of the third pairof contacts comprises a contact to p-type semiconductor.
 10. The LEDarray of claim 1, wherein the first wavelength is the shortestwavelength, the third wavelength is the longest wavelength, and thesecond wavelength is a wavelength between the first wavelength and thethird wavelength.
 11. The LED array of claim 3, further comprising athird pixel third tunnel junction on the third pixel third LED.
 12. Asystem comprising: the LED array of claim 1; an LED device attach regionhaving a first pair of electrodes coupled to the first pair of contactson the first pixel, a second pair of electrodes coupled to a second pairof contacts on the second pixel, and a third pair of electrodes coupledto a third pair of contacts on the third pixel; and driver circuitryconfigured to provide independent voltages to one or more of the firstpair of electrodes, the second pair of electrodes, and the third pair ofelectrodes.
 13. The system of claim 12, wherein the electronic system isselected from the group consisting of a LED-based luminaire, a lightemitting strip, a light emitting sheet, an optical display, and amicroLED display.
 14. The system of claim 12, further comprising: a VLCreceiver configured to convert a received light into data signals, theVLC receiver comprising an amplification circuit, an optical filter andconcentrator, a photodiode, and a clock and data recovery (CDR) unit.15. The system of claim 14, wherein the photodiode comprises one or moreof the first pixel, the second pixel, and the third pixel.
 16. Thesystem of claim 12, wherein the first wavelength is the shortestwavelength, the third wavelength is the longest wavelength, and thesecond wavelength is a wavelength between the first wavelength and thethird wavelength.
 17. A method comprising: receiving transmission data;converting the transmission data into a plurality of driving modulationsignals; providing a first voltage to first a pixel of a light emittingdiode (LED) array, based on the plurality of driving modulation signals,the first pixel comprising a first stack and having a first pair ofcontacts, the first pair of contacts comprising at least one firstcontact on a first pixel semiconductor layer on a first pixel tunneljunction, the first pixel tunnel junction on a first pixel LED on thesubstrate; providing a second voltage to a second pixel of the LED arraybased on the plurality of driving modulation signals, the first pixeland the second pixel separated by a first trench extending to asubstrate; and providing a third voltage to a third pixel of the LEDarray based on the plurality of driving modulation signals, wherein thefirst voltage causes the first pixel to emit a light of a firstwavelength, the second voltage causes the second pixel to emit a lightof a second wavelength, and the third voltage causes the third pixel toemit light of a third wavelength.
 18. The method of claim 17, whereinthe first voltage, the second voltage, and the third voltage areindependent from one another.
 19. The method of claim 17, wherein one ormore of the light of the first wavelength, the light of the secondwavelength, and the light of the third wavelength travel through thesubstrate, and wherein the first wavelength is the shortest wavelength,the third wavelength is the longest wavelength, and the secondwavelength is a wavelength between the first wavelength and the thirdwavelength.